Centrifugal blower sizing 1

[norm55]

Hello, can anyone inform me on how to determine what blower size and Horse power needed to develop 1100 cfm ?

 

[pennpoint]

norm55

At what pressure?

pennpoint

 

[norm55]

Pennpoint
low pressure around 10 psi

norm55

 

[ccw]

Hi norm55,

At 10 psi out (assuming ,input at 1 atm) you almost have a compressor. From Mach. Handbook 25th Ed. p.397, 10 psi at 1 CFM isothermal and adiabatic compression, HP required is 0.033. For 1100 CFM that would be roughly 0.033 x 1100 = 36.3 HP. Adding 15% for friction it would require 0.041 x 1100 = 45.1 HP.

 

[quark]

You can calculate BHP for adiabatic compression by the equation,

BHP = (4.36/1000)[k/(k-1)](cfm)(p1)[(p2/p1)^(k-1)/k-1]

where, k is ratio of specific heats(1.4 for diatomic gases including air), p1 is suction pressure in psia, p2 is discharge pressure in psia.

This yields to about 35.85HP. Then you have blower efficiency, transmission efficiency and motor efficiency. If I consider them to be 80%, 85% and 90%, your IHP will be 58.57HP.

You can use BHP = cfm*tp/6356 for fans where, tp is total pressure in inches of water(g)

You should size the blower for 1000cfm at 10psig

Regards,